The links in conveyor chains are subject to much wear as a result of the frictional engagement with sprockets or other driving mechanisms. Various means have been employed in the past to minimize such wear. In some cases, wear-resistant low friction material, outside bushings or rollers have been put on connecting links making up the chains. In many of the cases, the chains must be disassembled before such wear-resistant material can be put on the links. In other cases, such wear-resistant material has been expensive or impractical to use.
Chain links are used extensively in drag flight conveyor systems used in water and sewerage treatment plants, for example. One such application is described in a co-pending application of Hannum, Ser. No. #722,047, filed Apr. 11, 1985. Conveyor chains in such systems are generally driven or guided by sprocket wheels. A high degree of friction between the sprocket wheels and the connecting links of the chain subject the links and the sprockets to high wear. Such high wear ultimately results in the need to replace either the links or the sprocket wheels.
Snap-on wear pads minimize wear on conveyor chains are disclosed in a patent No. 4,114,467, issued Sept. 19, 1978. A typical conveyor link which may be made of plastic is described in a patent No. 3,881,593, issued May 6,1975.
The present invention relates to a novel bearing element for links in a conveyor chain. The bearing involves a type of structure which has been used in a number of applications involving springs, for example. These structures comprise metal strips which are wound into coils so that when they are unstressed they take the form of tightly wound spirals. When these springs are unwound and then released, the elements have a characteristic of returning to their original shapes. Such springs have been used to provide relatively constant pressure and have been used in steel tapes, pull-down shades, brush holders and the like.
Other characteristics of the coiled springs are dependent upon the particular design requirements. No claim is being made to a spring element or the process of making it, except as it relates to a bearing member to be described.